1This Laue centennial article has also been published in Zeitschrift für Kristallographie [Kubbinga (2012). Z. Kristallogr. 227, 1-26].

2Mitscherlich did not use formulae; for shortness' sake we here use those of Berzelius, upon whose chemistry Mitscherlich based his own.

3Red phosphorus was not yet known; it was discovered in 1847 by the Austrian chemist Anton Schrötter.

4The `integrant part' of Delafosse corresponds to the `subtractive molecule' of Haüy.

5Bravais, it is true, writes (ghk), but since it concerns evidently the `indices' that Miller had proposed in 1839, we stick to the latter's notation.

6Sohncke considered a similar distinction. His dilemma concerned the gaseous state, particularly that of sulfur.

7The mole concept had been introduced by Wilhelm Ostwald (1893) and propagated through the chemistry textbooks of Arnold F. Holleman in their countless editions (1898-). The number of molecules involved had been established by Jean Perrin (1908), who called it after Amedeo Avogadro. For the context, see Kubbinga (2009BB16), volume ii, pp. 520-527.